I have a Logitech Harmony Companion Remote and Hub. The remote has buttons for bulbs and for switches and to dim.
I wonder do I need a Philips Hue to use these buttons or can I directly connect them to my Hass and control my bulbs that is not in the Philips Hue Bridge?
You can use the Emulated Hue Bridge. I use this with mine.
Is possible then to control Z-Wave devices and groups that I have defined in Hass?
Yeah. You should be able to see anything you expose to the bridge. I only have lights exposed below is what i see in the harmony app.
Geeze, holy big picture, Batman!